Background: Central neuraxial anaesthesia may need to be supplemented with benzodiazapines, alpha2 blockers etc. for sedation and analgesia. In the present study, we compared the effects of intravenous dexmedetomidine and midazolam on sedation, postoperative analgesia, and spinal block duration in lower abdominal surgeries like inguinal hernias and appendicectomies performed under spinal anaesthesia. Methods: This prospective randomized controlled double blind study was carried out in 60 patients. Group D (n=30) received IV premedication with Dexmedetomidine 0.5mcg/kg while Group M (n=30) received IV Midazolam 0.05mg/kg fifteen minutes prior to subarachnoid block with bupivacaine 0.5% 3.5ml. Onset and duration of sensory and motor blockade, level of sedation, cardiorespiratory parameters and quality of postoperative analgesia were recorded. Results: The duration of sensory blockade was significantly prolonged in group D (280.00 ± 31.62 minutes) as compared to group M (263.00 ± 30.30 minutes) (p<0.05). The duration of analgesia was significantly prolonged in group D (261.50 ± 90.85minutes) than group M (213.67 ± 49.02minutes). The sedation scores were higher in group D as compared to group M in the beginning but comparable later on. The pulse rate was significantly decreased in group D than in group M. The systolic, diastolic and mean arterial pressures were significantly decreased in group M. There was no significant difference in respiratory rates in both the groups. Conclusion: IV premedication with dexmedetomidine 0.5 mcg/kg prolongs the duration of sensory blockade as compared to IV midazolam 0.05 mg/kg. Dexmedetomidine produces sedation with easy arousability, and provides better analgesia than midazolam.

Keywords: DexmedetoMidine; Midazolam; Premedication; Sedation; Spinal Anesthesia.